Friction spring unit



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, D. F SPROUL FRICTION SPRING UNIT Filed May 23, 1939 2 Sheets sheet l gg ai?.

w//M PLQ( D. F. SPROUL FRIGTION SPRING UNIT Filed may 29, 1939 :a sheets-sheet 2 Patented Mar. 18, 1941 AuNrriiD; STAT-Es PATENT yOFFICE well-Westinghouse Company,

Delaware a corporation of Application May 29, 1939, Serial No. 276,298

8 Claims.

This invention relates to railway trucks and more particularly to the spring supporting assembly therefor.

The principal object of the invention is the provision of a new and improved friction spring unit for use in connection with the bolster supporting springs of a railway car.

Another object of the invention is the provision of a new and improved friction spring unit that has novel means for mounting the spring in the unit so that the unit will not only assist in supporting the bolster but will function to prevent harmonic vibration of the entireassembly.

A further object of the invention is the provision of a new and improved friction spring unit having novel means for holding the parts in assembled relation.

A still further object of the invention is the provision of a new and improved friction spring unit that is inexpensive to manufacture, is easily assembled, that may be substituted for a conventional bolster supporting helical spring, that is efiicient in use, and that is sotconstructed as to prevent harmonic action of the bolster support- 25 ing helical spring.

Other and further objects and advantages of the invention will appear from the following description, taken in connection with the .accompanying drawings, in Which- Fig. 1 is a side elevation of a railway truck, with parts broken away and parts omitted for the sake of clearness;

Fig. 2 is a section on the line 2 2 of Fig. 3, with parts broken away;

Fig. 3 is a section on the line 3 3 of Fig. 2, with parts shown in full lines;

Fig. 4 is a section on the line 4-4 of Fig. 3;

Fig. 5 is a vertical section of the unit, with parts broken away, and showing the unit in compressed position;

Fig. 6 is a perspective view of one of the friction shoes looking from the inner side of the unit;

Fig. 7 is a perspective view looking from the outer side; and

Fig. 8 is a perspective view of one of the followers.

In railway trucks, the space for the spring assembly is very limited and since the trend in railway freight cars is in the direction of larger capacity cars and greater speeds, this restricted space for the spring assembly creates an ever increasingly diflicult problem. Every assembly of free acting springs has its natural period of vibration and if impulses due to iiatwheels `or joints in the rails areof such frequency, as `to (o1. 2cv-e) harmonize with the natural period of vibration of the assembly, this vertical vibration will continue to build up until it becomes objectionable. In order to dampen this vibration and at the same time increase the capacity cf the assembly 5 without the necessity of increasing the space for containing the same, Vthe present invention is especially adapted to be used with the conventional bolster supporting helical springs.

Referring now to the drawirms, the reference 10 character Ii) designates a truck for railway cars which comprises the side frame II having the bolster opening I3 therein with the end of the bolster I4 extending into said opening. The bolster is supported by a spring assembly I5 mount- 15 ed on the spring plank I6 which in turn rests on the tension member I'I of the side frame II. The spring assembly comprises a plurality of helical spring units I3, only one of which is shown, and one or more friction` spring units I9. This unit 20 is adapted to be substituted for one or more of the helical spring units at each side of the truck.

The friction spring unit I9 comprises what may be termed an upper follower 2 I, a lower follower 22 and a pair of shoes 23 and 2s between the fol- 25 lowers. The shoes are forced outwardly or apart by a plurality of spring units 25.

Since the followers 2| and 22 are substantially duplicates of each other, only one need be described. The follower 22, see Fig. 8, has its outer surface provided with fiat or parallel plane portions 26 and 27 which are connected together by the curved portions 2B and 29. The follower is provided with a pair of outwardly converging friction faces 3I and 3?.. Each of these faces is 5 a segment of a cylinder, as clearly shown in Fig.

8, and the two converge downwardly or outwardly in said figure. The bottom wall of the follower may, if desired, be provided with an opening 33 which will permit the escape of water and foreign matter that may collect in the follower during the use of the same. If desired, the followers may be hollow, as shown at 3i and 35 in Fig. 5, for decreasing their weight. 0n the inner sides of the at portions 26 and 21 of the followers are provided the recesses 33 and 3l, which are duplicates of each other. These recesses are each provided' with overhanging portions 38 and 39 forming retaining shoul- 5o ders at opposite sides of each recess. These shoulders 33 and 39 are spaced apart for forming a passageway for suitable retaining lugs on the shoes, as will presently appear. The bottom wall `of `therecess is in avertical plane which extends 55 to the inner and upper edge of the follower, as shown in Fig. 8.

The friction shoes 25 and 24 are each provided with curved friction surfaces 4i and 42, Fig. 7, at the ends thereof. The curvature of these friction surfaces corresponds to the curvature of the friction surfaces 3l and 32 of the cap member, that is, these friction surfaces are segments of cylinders and converge axially outwardly.

Suitable means are provided for holding the parts in assembled relation. In the form of the construction shown, the recesses 3S and 3l and the overhanging projections 38 and 39 are utilized for this purpose. Each of the friction shoes or wedge members is provided with two projections or lugs i3 and lll at each side thereof which are adapted `to engage beneath the ledges or shoulders 3S and 39 for limiting the outward movement of the followers. These lugs may, if desired, be triangular in cross-section having inclined surfaces which conform to the corresponding inclined wall, the recess of which is the same as that of the wedge surfaces 3 I, 32.

Each of the wedge members is provided with a recess 45 for receiving the ends of the spring Z5, In the form of the construction shown, each of these recesses is in the form of an yhourglass or a figure eight so as to econornize inspace by assembling the springs closely adjacent. These recesses receive the ends of the two spring units.

The springunits may be of any suitable construction. In the form shown, they are helical and each is of the double spring type, Ythat is, there is an outer helical spring 45 and an inner vhelical spring Lil, the springunits 25 being arranged in a vertical plane, as shown in Fig. 2. The friction spring unit is assembled by placing the spring units Z in position in the shoes, then forcing the shoes toward each other to compress the springs 25 and while the springs are being held compressed with Vthe shoes in contact with each other, as shownin Fig. 5, the followers may be placed in position on Vthe end of the shoes and the shoes then released. The parts are so constructed that when the shoes are held in contact or nearly so while assembling the device, the projections t3, 124 are close enough together to'pass between the overhanging ledges 38 and 30 and are spaced a sufficient distance from the ends of the shoes so that when the shoes are released, they will moveoutwardly beneath theseV ledges, as indicated in Fig. 3, which will hold the parts in assembled relation and limit the outward movement of the followers.

In the operation of the device, when load or force is applied to the followers, they will move toward each other. This movement of the followers will tend to force the shoes radially inwardly due to the contacting wedge faces of the followers and shoes. rThis movement will be resisted by the springs 25 thereby creating considerable friction between the'friction surfaces on the shoes and followers. Upon release, the

springs will force the shoesy apart which in turn will react on the followers to force them cutwardly.

Preferably, though not necessarily, the parts are so constructed that on overload, the friction shoes' 23 and 24 will engage the end walls 48 and 49,. Fig. ,2, of the followers 2l `and 22 for limiting the compression of the unit. As shown, the shoes engage these end walls before the shoes engage each other and-before the springs go solid whereby the springs are protected from being overoompressed upon compression of the unit.

It will thus be seen that the frictional resistance to the compression of the friction spring unit will not only prevent harmonic vibration of the spring assembly but this frictional resistance to the compression of this unit very greatly increases the capacity of the spring assembly.

It is thought from the foregoing, taken in connection with the accompanying drawings, that the construction and operation of my device will be apparent to those skilled in the art and that changes in size, shape, proportion and detail may be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A spring unit for a bolster supporting spring assembly comprising a pair of followers, each having outwardly converging friction surfaces, a pair of friction shoes, each having a straight body portion provided with an outer surface curved in cross-section and each having an inclined friction surface on each end engaging the friction surfaces of said followers, a pin and slot connection between each end of each shoe and the corresponding followers, said pins extending at right angles to thel axes of said spring means, and spring means. for forcing said, shoes into frictional engagement with the friction surfaces of said followers, said spring means constituting the sole spring membersY employed for resisting compression of said unit.

2. A spring unit for use in bolster supporting spring assembly comprising a pair of opposed followers, each follower provided with a straight body portion having at its ends friction surfaces converging outwardly, laterally extending lugs at each side of each shoeat the ends thereof for engaging recesses insaid'followers for limiting the expansion of said unit, each surface being a segment of a cylinder, a pair of opposed shoes having friction surfaces engaging the friction surfaces of said followers and conforming thereto, and resilient means for forcing said shoes apart radially, said means constituting the sole resilient elements of said unit.

3. In a spring assembly, a friction spring unit comprising a pair of opposed followers, each follower having segmental cylindrical wedging surfaces converging outwardly, a pair of opposed friction shoes having segmental cylindrical wedging faces convergingvoutwardly for engaging said wedging surfaces, and horizontally arranged springs between said shoes, said followers being provided with flat portions vhaving recesses therein having overhanging shoulders with a passageway between said shoulders for receiving lugs integral with said shoes in'assembling the unit.

4. A spring unit for a bolster supporting spring assembly comprising a pair of followers, each having outwardly converging friction surfaces, a pair of friction shoes, each having a friction surface on each end engaging the friction surfaces of said followers, spring means for forcing said shoes into frictional engagement with the friction surfaces-of said followers, the parts being so constructed that said means is adapted to restore the parts to normal inoperative position after release, and cooperating means on said followers and the sides of said shoes for limiting the expansion of said unit, said means comprising lugs on one cooperating member extending at right angles to the axis of said springs and engaging recesses in the other of said cooperating members.

5. A spring unit for use in a bolster supporting spring assembly comprising a pair of opposed followers, each follower having friction surfaces converging outwardly, each surface being a segnient of a cylinder, a pair of opposed shoes having friction surfaces engaging the friction surfaces of said followers and conforming thereto, resilient means for forcing said shoes apart radially, and means for holding the parts in assembled relation, said means comprising laterally extending lugs on each end of each shoe engaging in recesses in a fiat portion of the side Walls of said followers beneath overhanging ledges.

6. In a friction spring unit, a follower in the form of a cap member having a bottom wall, an upstanding side wall, said side wall having opposite plane sides parallel and connected together with curved portions, said plane sides being pro vided on their inner surfaces with recesses having overhanging shoulders forming passages to the recesses, and said curved walls being provided on their inner surfaces with segmental cylindrical friction surfaces converging toward the bottom wall.

7. In a friction spring unit, a wedge member provided with plain .side faces and having an inner side plane and the outer curved, retaining lugs extending laterally from said side faces at each end of said member, segmental cylindrical wedging faces on the ends of said Wedge member on its outer side, said member having an B-shaped recess on its plane surface.

8. A spring unit for a bolster supporting spring assembly comprising a pair of followers, each having outwardly converging friction surfaces merging in a bottom wall, a pair of friction shoes, each having a friction surface on each end engaging the friction surfaces of said followers, each shoe having an S-Shaped recess on its inner surface, a pair of spring units seated in each recess for resisting the compression of said unit,

the length of said shoes being such that the ends` thereof engage said bottom walls before said spring units go solid, and means for holding the parts in assembled relation, said means comprising laterally extending lugs on each end of each shoe engaging in recesses in the side walls of said followers.

DONALD F. SPROUL. 

